The present invention relates to an image forming apparatus that forms an image on a sheet in accordance with image data.
There are known various types of image forming apparatuses each forming an image on a sheet in accordance with image data. For example, a printer for outputting on a sheet image data transmitted from a computer and a copying machine that reads images from a surface of a document to copy them are known. With speeding up and cost reduction, these image forming apparatuses are coming into wide use rapidly among offices and homes.
In offices, a large number of documents are made every day by these image forming apparatuses. A print job to output a large number of sets of documents is frequently executed, under the condition that one set contains plural pages.
Incidentally, especially in the office, there is an occasion where an outputting job has to be discontinued halfway during the output of a large number of documents, because of circumstances of on-the-job hours. When discontinuing printing for a large number of sets, there is considered a method to output again from the beginning on the next day. However, this method is extremely disadvantageous in terms of productivity.
Therefore, there is proposed a technology to restart a discontinued print job, on the next day, from the point in the print job where that print job was discontinued (for example, see “Patent Document” 1” and “Patent Document 2”). In the proposed technology, what should be done before the power of the image forming apparatus is turned off is to cause a print job in execution to be evacuated to a nonvolatile memory where contents of data do not disappear even if the power is turned off. On the evacuated print job, there is information showing the number of outputted sets and outputted pages. After power-on again, image forming is restarted from the page on the way, referring to the print job evacuated to a nonvolatile memory. In other words, the proposed technology is one to make arrangements for the restart before the power is turned off.
Then, when the power is turned on again, an existence of the unfinished print job is notified, and it is possible to select whether to restart the print job that was in execution before the discontinuation from the page on the way, or to restart from the forefront of the set, or to try again form the beginning, and the print job which has been in execution is executed depending on the result of the selection.
In the conventional technology to make arrangements for the restart before the power is turned off, the main purpose is to restart from the printing on the way. Therefore, when the printing is still on the way of the set, the printing is discontinued on the way of the set.
Printing forms include printing of documents in which each set has a meaning, in other words, printing of a booklet that has a meaning only when plural pages are assembled in one, and in particular, a printing form to make a booklet by conducting staple processing and wrapping binding processing. In the printing form of documents where each set has a meaning of this kind, if image forming is discontinued immediately in spite of a halfway portion of the set, printed bundles up to the halfway point of the set before the discontinuation and printed-bundles from the halfway point of the set after the restart up to the end result in a useless outputted object. Further, if this set which resulted in a useless outputted object is not tried to print again, desired number of outputted sets are not obtained.
When the power is turned on again, there is a possibility that the discontinuation is on the halfway point of a set. Therefore, it is essential to urge a user to select whether to restart the print job which was in execution from the page on the way or whether to restart from the forefront of the set. However, a person who uses the image forming apparatus first after repower-on is not necessarily a person who requires the print job which was in execution before the discontinuation. When a person who uses the image forming apparatus first after the repower-on is a different person, it is unclear whether a person who required the print job which was in execution before the discontinuation keeps the prints which became a separated part of the set, or whether the person has scrapped the prints, which causes confusion for selection.
[Patent Document 1] Japanese Patent Publication Open to Public Inspection No. 2005-22099
[Patent Document 2] Japanese Patent Publication Open to Public Inspection No. 2006-35533